Periodontitis is a chronic inflammatory disease that is believed to result from an imbalance between the microbial assault and the host immune reaction. Rheumatoid arthritis is believed to be an autoimmune disease and to have a pathogenesis somewhat similar to the pathogenesis of periodontitis. Diabetes mellitus is a group of metabolic disorders of carbohydrate metabolism, and with a concomitant vascular changes. There are controversial findings about the association between these two debilitating diseases and the occurrence of periodontal tissue breakdown. The NHANES III data will be used to substantiate a hypotheses of no relationship between rheumatoid arthritis, diabetes mellitus and periodontitis.